<?php

/**
 * @file view.inc
 * Provides the view object type and associated methods.
 */
/**
 * @defgroup views_objects Objects that represent a View or part of a view.
 * @{
 * These objects are the core of Views do the bulk of the direction and
 * storing of data. All database activity is in these objects.
 */

/**
 * An object to contain all of the data to generate a view, plus the member
 * functions to build the view query, execute the query and render the output.
 */
class view extends views_db_object {

    var $db_table = 'views_view';
    var $base_table = 'node';
    // State variables
    var $built = FALSE;
    var $executed = FALSE;
    var $args = array();
    var $build_info = array();
    var $use_ajax = FALSE;
    // Where the results of a query will go.
    var $result = array();
    // pager variables
    var $pager = array(
        'use_pager' => FALSE,
        'items_per_page' => 10,
        'element' => 0,
        'offset' => 0,
        'current_page' => 0,
    );
    // Places to put attached renderings:
    var $attachment_before = '';
    var $attachment_after = '';
    // Exposed widget input
    var $exposed_data = array();
    var $exposed_input = array();
    // Used to store views that were previously running if we recurse.
    var $old_view = array();

    /**
     * Identifier of the current display.
     *
     * @var string
     */
    var $current_display;

    /**
     * Stores all the views substitutions.
     */
    var $substitutions = array();

    /**
     * Constructor
     */
    function view() {
        parent::init();
        // Make sure all of our sub objects are arrays.
        foreach ($this->db_objects() as $object) {
            $this->$object = array();
        }

        $this->query = new stdClass();
    }

    /**
     * Returns a list of the sub-object types used by this view. These types are
     * stored on the display, and are used in the build process.
     */
    function display_objects() {
        return array('argument', 'field', 'sort', 'filter', 'relationship');
    }

    /**
     * Returns the complete list of dependent objects in a view, for the purpose
     * of initialization and loading/saving to/from the database.
     *
     * Note: In PHP5 this should be static, but PHP4 doesn't support static
     * methods.
     */
    function db_objects() {
        return array('display');
    }

    /**
     * Set the arguments that come to this view. Usually from the URL
     * but possibly from elsewhere.
     */
    function set_arguments($args) {
        $this->args = $args;
    }

    /**
     * Set the page size for ranged or pager queries
     */
    function set_items_per_page($items_per_page) {
        $this->pager['items_per_page'] = $items_per_page;
        if (empty($items_per_page)) {
            $this->pager['use_pager'] = FALSE;
        }
    }

    /**
     * Change/Set the current page for the pager.
     */
    function set_current_page($page) {
        $this->pager['current_page'] = $page;
    }

    /**
     * Whether or not the pager should be used.
     */
    function set_use_pager($use_pager) {
        $this->pager['use_pager'] = $use_pager;
    }

    /**
     * The pager element id to use if use_apger is on
     */
    function set_pager_element($pager_element) {
        $this->pager['element'] = $pager_element;
    }

    /**
     * Synchronize views pager with global pager variables
     *
     */
    function synchronize_pager() {
        if (!empty($this->pager['use_pager'])) {
            // dump information about what we already know into the globals
            global $pager_page_array, $pager_total, $pager_total_items;
            // total rows in query
            $pager_total_items[$this->pager['element']] = $this->total_rows;
            // total pages
            $pager_total[$this->pager['element']] = ceil($pager_total_items[$this->pager['element']] / $this->pager['items_per_page']);

            // What page was requested:
            $pager_page_array = isset($_GET['page']) ? explode(',', $_GET['page']) : array();

            // If the requested page was within range. $this->pager['current_page']
            // defaults to 0 so we don't need to set it in an out-of-range condition.
            if (!empty($pager_page_array[$this->pager['element']])) {
                $page = intval($pager_page_array[$this->pager['element']]);
                if ($page > 0 && $page < $pager_total[$this->pager['element']]) {
                    $this->pager['current_page'] = $page;
                }
            }
            $pager_page_array[$this->pager['element']] = $this->pager['current_page'];
        }
    }

    /**
     * How many records to skip. This does not function if use_pager is
     * set.
     */
    function set_offset($offset) {
        $this->pager['offset'] = $offset;
    }

    /**
     * Whether or not AJAX should be used. If AJAX is used, paging,
     * tablesorting and exposed filters will be fetched via an AJAX call
     * rather than a page refresh.
     */
    function set_use_ajax($use_ajax) {
        $this->use_ajax = $use_ajax;
    }

    /**
     * Set the exposed filters input to an array. If unset they will be taken
     * from $_GET when the time comes.
     */
    function set_exposed_input($filters) {
        $this->exposed_input = $filters;
    }

    /**
     * Figure out what the exposed input for this view is.
     */
    function get_exposed_input() {
        // Fill our input either from $_GET or from something previously set on the
        // view.
        if (empty($this->exposed_input)) {
            $this->exposed_input = $_GET;
            // unset items that are definitely not our input:
            foreach (array('page', 'q') as $key) {
                if (isset($this->exposed_input[$key])) {
                    unset($this->exposed_input[$key]);
                }
            }

            // If we have no input at all, check for remembered input via session.
            // If filters are not overridden, store the 'remember' settings on the
            // default display. If they are, store them on this display. This way,
            // multiple displays in the same view can share the same filters and
            // remember settings.
            $display_id = ($this->display_handler->is_defaulted('filters')) ? 'default' : $this->current_display;

            if (empty($this->exposed_input) && !empty($_SESSION['views'][$this->name][$display_id])) {
                $this->exposed_input = $_SESSION['views'][$this->name][$display_id];
            }
        }

        return $this->exposed_input;
    }

    /**
     * Set the display for this view and initialize the display handler.
     */
    function init_display($reset = FALSE) {
        // The default display is always the first one in the list.
        if (isset($this->current_display)) {
            return TRUE;
        }

        // Instantiate all displays
        foreach (array_keys($this->display) as $id) {
            // Correct for shallow cloning
            // Often we'll have a cloned view so we don't mess up each other's
            // displays, but the clone is pretty shallow and doesn't necessarily
            // clone the displays. We can tell this by looking to see if a handler
            // has already been set; if it has, but $this->current_display is not
            // set, then something is dreadfully wrong.
            if (!empty($this->display[$id]->handler)) {
                $this->display[$id] = drupal_clone($this->display[$id]);
                unset($this->display[$id]->handler);
            }
            $this->display[$id]->handler = views_get_plugin('display', $this->display[$id]->display_plugin);
            if (!empty($this->display[$id]->handler)) {
                // Initialize the new display handler with data.
                $this->display[$id]->handler->init($this, $this->display[$id]);
                // If this is NOT the default display handler, let it know which is
                // since it may well utilize some data from the default.
                // This assumes that the 'default' handler is always first. It always
                // is. Make sure of it.
                if ($id != 'default') {
                    $this->display[$id]->handler->default_display = &$this->display['default']->handler;
                }
            }
        }

        $this->current_display = 'default';
        $this->display_handler = &$this->display['default']->handler;

        return TRUE;
    }

    /**
     * Get the first display that is accessible to the user.
     *
     * @param $displays
     *   Either a single display id or an array of display ids.
     */
    function choose_display($displays) {
        if (!is_array($displays)) {
            return $displays;
        }

        $this->init_display();

        foreach ($displays as $display_id) {
            if ($this->display[$display_id]->handler->access()) {
                return $display_id;
            }
        }

        return 'default';
    }

    /**
     * Set the display as current.
     *
     * @param $display_id
     *   The id of the display to mark as current.
     */
    function set_display($display_id = NULL) {
        // If we have not already initialized the display, do so. But be careful.
        if (empty($this->current_display)) {
            $this->init_display();

            // If handlers were not initialized, and no argument was sent, set up
            // to the default display.
            if (empty($display_id)) {
                $display_id = 'default';
            }
        }

        $display_id = $this->choose_display($display_id);

        // If no display id sent in and one wasn't chosen above, we're finished.
        if (empty($display_id)) {
            return FALSE;
        }

        // Ensure the requested display exists.
        if (empty($this->display[$display_id])) {
            $display_id = 'default';
            if (empty($this->display[$display_id])) {
                vpr(t('set_display() called with invalid display id @display.', array('@display' => $display_id)));
                return FALSE;
            }
        }

        // Set the current display.
        $this->current_display = $display_id;

        // Ensure requested display has a working handler.
        if (empty($this->display[$display_id]->handler)) {
            return FALSE;
        }

        // Set a shortcut
        $this->display_handler = &$this->display[$display_id]->handler;

        return TRUE;
    }

    /**
     * Find and initialize the style plugin.
     *
     * Note that arguments may have changed which style plugin we use, so
     * check the view object first, then ask the display handler.
     */
    function init_style() {
        if (isset($this->style_plugin)) {
            return is_object($this->style_plugin);
        }

        if (!isset($this->plugin_name)) {
            $this->plugin_name = $this->display_handler->get_option('style_plugin');
            $this->style_options = $this->display_handler->get_option('style_options');
        }

        $this->style_plugin = views_get_plugin('style', $this->plugin_name);

        if (empty($this->style_plugin)) {
            return FALSE;
        }

        // init the new style handler with data.
        $this->style_plugin->init($this, $this->display[$this->current_display], $this->style_options);
        return TRUE;
    }

    /**
     * Acquire and attach all of the handlers.
     */
    function init_handlers() {
        if (empty($this->inited)) {
            foreach (views_object_types() as $key => $info) {
                $this->_init_handler($key, $info);
            }
            $this->inited = TRUE;
        }
    }

    /**
     * Create a list of base tables eligible for this view. Used primarily
     * for the UI. Display must be already initialized.
     */
    function get_base_tables() {
        $base_tables = array(
            $this->base_table => TRUE,
            '#global' => TRUE,
        );

        foreach ($this->display_handler->get_handlers('relationship') as $handler) {
            $base_tables[$handler->definition['base']] = TRUE;
        }
        return $base_tables;
    }

    /**
     * Run the pre_query() on all active handlers.
     */
    function _pre_query() {
        foreach (views_object_types() as $key => $info) {
            $handlers = &$this->$key;
            $position = 0;
            foreach ($handlers as $id => $handler) {
                $handlers[$id]->position = $position;
                $handlers[$id]->pre_query();
                $position++;
            }
        }
    }

    /**
     * Get's all the substitutions and store them.
     */
    function substitutions($reset = FALSE) {
        if ($reset || empty($this->substitutions)) {
            $this->substitutions = module_invoke_all('views_query_substitutions', $this);
        }
        return $this->substitutions;
    }

    /**
     * Attach all of the handlers for each type.
     *
     * @param $key
     *   One of 'argument', 'field', 'sort', 'filter', 'relationship'
     * @param $info
     *   The $info from views_object_types for this object.
     */
    function _init_handler($key, $info) {
        // Load the requested items from the display onto the object.
        $this->$key = $this->display_handler->get_handlers($key);

        // This reference deals with difficult PHP indirection.
        $handlers = &$this->$key;

        // Run through and test for accessibility.
        foreach ($handlers as $id => $handler) {
            if (!$handler->access()) {
                unset($handlers[$id]);
            }
        }
    }

    /**
     * Render the exposed filter form.
     *
     * This actually does more than that; because it's using FAPI, the form will
     * also assign data to the appropriate handlers for use in building the
     * query.
     */
    function render_exposed_form($block = FALSE) {
        // Deal with any exposed filters we may have, before building.
        $form_state = array(
            'view' => &$this,
            'display' => &$this->display_handler->display,
            'method' => 'get',
            'rerender' => TRUE,
            'no_redirect' => TRUE,
        );

        // Some types of displays (eg. attachments) may wish to use the exposed
        // filters of their parent displays instead of showing an additional
        // exposed filter form for the attachment as well as that for the parent.
        if (!$this->display_handler->displays_exposed() || (!$block && $this->display_handler->get_option('exposed_block'))) {
            unset($form_state['rerender']);
        }

        if (!empty($this->ajax)) {
            $form_state['ajax'] = TRUE;
        }

        $output = drupal_build_form('views_exposed_form', $form_state);
        if (!empty($form_state['js settings'])) {
            $this->js_settings = $form_state['js settings'];
        }

        // Don't render exposed filter form when there's form errors.
        // Applies when filters are in a block ("exposed_block" option).
        if (form_get_errors() && empty($form_state['rerender'])) {
            return NULL;
        }

        return $output;
    }

    /**
     * Build all the arguments.
     */
    function _build_arguments() {
        // Initially, we want to build sorts and fields. This can change, though,
        // if we get a summary view.
        if (empty($this->argument)) {
            return TRUE;
        }

        // build arguments.
        $position = -1;

        // Create a title for use in the breadcrumb trail.
        $title = $this->display_handler->get_option('title');

        $this->build_info['breadcrumb'] = array();
        $breadcrumb_args = array();
        $substitutions = array();

        $status = TRUE;

        // Iterate through each argument and process.
        foreach ($this->argument as $id => $arg) {
            $position++;
            $argument = &$this->argument[$id];

            if ($argument->broken()) {
                continue;
            }

            $argument->set_relationship();

            $arg = isset($this->args[$position]) ? $this->args[$position] : NULL;
            $argument->position = $position;

            if (isset($arg) || $argument->has_default_argument()) {
                if (!isset($arg)) {
                    $arg = $argument->get_default_argument();
                    // make sure default args get put back.
                    if (isset($arg)) {
                        $this->args[$position] = $arg;
                    }
                }

                // Set the argument, which will also validate that the argument can be set.
                if (!$argument->set_argument($arg)) {
                    $status = $argument->validate_fail($arg);
                    break;
                }

                if ($argument->is_wildcard()) {
                    $arg_title = $argument->wildcard_title();
                } else {
                    $arg_title = $argument->get_title();
                    $argument->query();
                }

                // Add this argument's substitution
                $substitutions['%' . ($position + 1)] = $arg_title;

                // Since we're really generating the breadcrumb for the item above us,
                // check the default action of this argument.
                if ($this->display_handler->uses_breadcrumb() && $argument->uses_breadcrumb()) {
                    $path = $this->get_url($breadcrumb_args);
                    if (strpos($path, '%') === FALSE) {
                        $breadcrumb = !empty($argument->options['breadcrumb']) ? $argument->options['breadcrumb'] : $title;
                        $this->build_info['breadcrumb'][$path] = str_replace(array_keys($substitutions), $substitutions, $breadcrumb);
                    }
                }

                // Allow the argument to muck with this breadcrumb.
                $argument->set_breadcrumb($this->build_info['breadcrumb']);

                // Test to see if we should use this argument's title
                if (!empty($argument->options['title'])) {
                    $title = $argument->options['title'];
                }

                $breadcrumb_args[] = $arg;
            } else {
                // determine default condition and handle.
                $status = $argument->default_action();
                break;
            }

            // Be safe with references and loops:
            unset($argument);
        }

        // set the title in the build info.
        if (!empty($title)) {
            $this->build_info['title'] = str_replace(array_keys($substitutions), $substitutions, $title);
        }

        // Store the arguments for later use.
        $this->build_info['substitutions'] = $substitutions;

        return $status;
    }

    /**
     * Do some common building initialization.
     */
    function init_query() {
        // Create and initialize the query object.
        $views_data = views_fetch_data($this->base_table);
        $this->base_field = $views_data['table']['base']['field'];
        if (!empty($views_data['table']['base']['database'])) {
            $this->base_database = $views_data['table']['base']['database'];
        }
        views_include('query');
        $this->query = new views_query($this->base_table, $this->base_field);
    }

    /**
     * Build the query for the view.
     */
    function build($display_id = NULL) {
        if (!empty($this->built)) {
            return;
        }

        if (empty($this->current_display) || $display_id) {
            if (!$this->set_display($display_id)) {
                return FALSE;
            }
        }

        // Let modules modify the view just prior to building it.
        foreach (module_implements('views_pre_build') as $module) {
            $function = $module . '_views_pre_build';
            $function($this);
        }

        // Attempt to load from cache.
        // @todo Load a build_info from cache.

        $start = views_microtime();
        // If that fails, let's build!
        $this->build_info = array(
            'query' => '',
            'count_query' => '',
            'query_args' => array(),
        );

        $this->init_query();

        // Call a module hook and see if it wants to present us with a
        // pre-built query or instruct us not to build the query for
        // some reason.
        // @todo: Implement this. Use the same mechanism Panels uses.
        // Run through our handlers and ensure they have necessary information.
        $this->init_handlers();

        // Let the handlers interact with each other if they really want.
        $this->_pre_query();

        if ($this->display_handler->uses_exposed()) {
            $this->exposed_widgets = $this->render_exposed_form();
            if (form_set_error() || !empty($this->build_info['abort'])) {
                $this->built = TRUE;
                // Don't execute the query, but rendering will still be executed to display the empty text.
                $this->executed = TRUE;
                return empty($this->build_info['fail']);
            }
        }

        // Build all the relationships first thing.
        $this->_build('relationship');

        // Build all the filters.
        $this->_build('filter');

        $this->build_sort = TRUE;

        // Arguments can, in fact, cause this whole thing to abort.
        if (!$this->_build_arguments()) {
            $this->build_time = views_microtime() - $start;
            $this->attach_displays();
            return $this->built;
        }

        // Initialize the style; arguments may have changed which style we use,
        // so waiting as long as possible is important. But we need to know
        // about the style when we go to build fields.
        if (!$this->init_style()) {
            $this->build_info['fail'] = TRUE;
            return FALSE;
        }

        if ($this->style_plugin->uses_fields()) {
            $this->_build('field');
        }

        // Build our sort criteria if we were instructed to do so.
        if (!empty($this->build_sort)) {
            // Allow the style handler to deal with sorting.
            if ($this->style_plugin->build_sort()) {
                $this->_build('sort');
            }
            // allow the plugin to build second sorts as well.
            $this->style_plugin->build_sort_post();
        }

        // Allow display handler to affect the query:
        $this->display_handler->query();

        // Allow style handler to affect the query:
        $this->style_plugin->query();

        if (variable_get('views_sql_signature', FALSE)) {
            $this->query->add_field(NULL, "'" . $this->name . ':' . $this->current_display . "'", 'view_name');
        }

        // Let modules modify the query just prior to finalizing it.
        foreach (module_implements('views_query_alter') as $module) {
            $function = $module . '_views_query_alter';
            $function($this, $this->query);
        }

        $this->build_info['query'] = $this->query->query();
        $this->build_info['count_query'] = $this->query->query(TRUE);
        $this->build_info['query_args'] = $this->query->get_where_args();
        $this->built = TRUE;
        $this->build_time = views_microtime() - $start;

        // Attach displays
        $this->attach_displays();

        // Let modules modify the view just after building it.
        foreach (module_implements('views_post_build') as $module) {
            $function = $module . '_views_post_build';
            $function($this);
        }

        return TRUE;
    }

    /**
     * Internal method to build an individual set of handlers.
     */
    function _build($key) {
        $handlers = &$this->$key;
        foreach ($handlers as $id => $data) {
            if (!empty($handlers[$id]) && is_object($handlers[$id])) {
                // Give this handler access to the exposed filter input.
                if (!empty($this->exposed_data)) {
                    $rc = $handlers[$id]->accept_exposed_input($this->exposed_data);
                    $handlers[$id]->store_exposed_input($this->exposed_data, $rc);
                    if (!$rc) {
                        continue;
                    }
                }
                $handlers[$id]->set_relationship();
                $handlers[$id]->query();
            }
        }
    }

    /**
     * Execute the view's query.
     */
    function execute($display_id = NULL) {
        if (empty($this->built)) {
            if (!$this->build($display_id)) {
                return FALSE;
            }
        }

        if (!empty($this->executed)) {
            return TRUE;
        }

        // Let modules modify the view just prior to executing it.
        foreach (module_implements('views_pre_execute') as $module) {
            $function = $module . '_views_pre_execute';
            $function($this);
        }

        $query = db_rewrite_sql($this->build_info['query'], $this->base_table, $this->base_field, array('view' => &$this));
        $count_query = db_rewrite_sql($this->build_info['count_query'], $this->base_table, $this->base_field, array('view' => &$this));

        $args = $this->build_info['query_args'];

        vpr($query);


        // Check for already-cached results.
        if (!empty($this->live_preview)) {
            $cache = FALSE;
        } else {
            $cache = $this->display_handler->get_cache_plugin();
        }
        if ($cache && $cache->cache_get('results')) {
            $this->synchronize_pager();
            vpr('Used cached results');
        } else {
            $items = array();
            if ($query) {
                $replacements = $this->substitutions();
                $query = str_replace(array_keys($replacements), $replacements, $query);
                $count_query = 'SELECT COUNT(*) FROM (' . str_replace(array_keys($replacements), $replacements, $count_query) . ') count_alias';

                if (is_array($args)) {
                    foreach ($args as $id => $arg) {
                        $args[$id] = str_replace(array_keys($replacements), $replacements, $arg);
                    }
                }

                // Allow for a view to query an external database.
                if (isset($this->base_database)) {
                    db_set_active($this->base_database);
                    $external = TRUE;
                }

                $start = views_microtime();
                if (!empty($this->pager['items_per_page'])) {
                    // We no longer use pager_query() here because pager_query() does not
                    // support an offset. This is fine as we don't actually need pager
                    // query; we've already been doing most of what it does, and we
                    // just need to do a little more playing with globals.
                    if (!empty($this->pager['use_pager']) || !empty($this->get_total_rows)) {
                        $this->total_rows = db_result(db_query($count_query, $args)) - $this->pager['offset'];
                    }

                    $this->synchronize_pager();
                    $offset = $this->pager['current_page'] * $this->pager['items_per_page'] + $this->pager['offset'];
                    $result = db_query_range($query, $args, $offset, $this->pager['items_per_page']);
                } else {
                    $result = db_query($query, $args);
                }

                $this->result = array();
                while ($item = db_fetch_object($result)) {
                    $this->result[] = $item;
                }

                // If we already know how many items we have even if we did not run the
                // count query, go ahead and set that value:
                if (empty($this->pager['items_per_page'])) {
                    $this->total_rows = count($this->result);
                }

                if (!empty($external)) {
                    db_set_active();
                }
                $this->execute_time = views_microtime() - $start;
            }
            if ($cache) {
                $cache->cache_set('results');
            }
        }

        // Let modules modify the view just after executing it.
        foreach (module_implements('views_post_execute') as $module) {
            $function = $module . '_views_post_execute';
            $function($this);
        }

        $this->executed = TRUE;
    }

    /**
     * Render this view for display.
     */
    function render($display_id = NULL) {
        $this->execute($display_id);

        // Check to see if the build failed.
        if (!empty($this->build_info['fail'])) {
            return;
        }

        init_theme();

        $start = views_microtime();
        if (!empty($this->live_preview) && variable_get('views_show_additional_queries', FALSE)) {
            $this->start_query_capture();
        }

        // Check for already-cached output.
        if (!empty($this->live_preview)) {
            $cache = FALSE;
        } else {
            $cache = $this->display_handler->get_cache_plugin();
        }
        if ($cache && $cache->cache_get('output')) {
            vpr('Used cached output');
        } else {
            if ($cache) {
                $cache->cache_start();
            }

            // Initialize the style plugin.
            $this->init_style();

            $this->style_plugin->pre_render($this->result);

            // Let modules modify the view just prior to rendering it.
            foreach (module_implements('views_pre_render') as $module) {
                $function = $module . '_views_pre_render';
                $function($this);
            }

            // Let the theme play too, because pre render is a very themey thing.
            $function = $GLOBALS['theme'] . '_views_pre_render';
            if (function_exists($function)) {
                $function($this);
            }

            // Give field handlers the opportunity to perform additional queries
            // using the entire resultset prior to rendering.
            if ($this->style_plugin->uses_fields()) {
                foreach ($this->field as $id => $handler) {
                    if (!empty($this->field[$id])) {
                        $this->field[$id]->pre_render($this->result);
                    }
                }
            }
            $this->display_handler->output = $this->display_handler->render();
            if ($cache) {
                $cache->cache_set('output');
            }
        }

        if ($cache) {
            $cache->post_render($this->display_handler->output);
        }

        // Let modules modify the view output after it is rendered.
        foreach (module_implements('views_post_render') as $module) {
            $function = $module . '_views_post_render';
            $function($this, $this->display_handler->output, $cache);
        }

        // Let the theme play too, because post render is a very themey thing.
        $function = $GLOBALS['theme'] . '_views_post_render';
        if (function_exists($function)) {
            $function($this, $this->display_handler->output, $cache);
        }

        if (!empty($this->live_preview) && variable_get('views_show_additional_queries', FALSE)) {
            $this->end_query_capture();
        }
        $this->render_time = views_microtime() - $start;

        return $this->display_handler->output;
    }

    /**
     * Render a specific field via the field ID and the row #.
     */
    function render_field($field, $row) {
        if (isset($this->field[$field]) && isset($this->result[$row])) {
            return $this->field[$field]->advanced_render($this->result[$row]);
        }
    }

    /**
     * Execute the given display, with the given arguments.
     * To be called externally by whatever mechanism invokes the view,
     * such as a page callback, hook_block, etc.
     *
     * This function should NOT be used by anything external as this
     * returns data in the format specified by the display. It can also
     * have other side effects that are only intended for the 'proper'
     * use of the display, such as setting page titles and breadcrumbs.
     *
     * If you simply want to view the display, use view::preview() instead.
     */
    function execute_display($display_id = NULL, $args = array()) {
        if (empty($this->current_display) || $this->current_display != $this->choose_display($display_id)) {
            if (!$this->set_display($display_id)) {
                return FALSE;
            }
        }

        $this->pre_execute($args);

        // Execute the view
        $output = $this->display_handler->execute();

        $this->post_execute();
        return $output;
    }

    /**
     * Preview the given display, with the given arguments.
     *
     * To be called externally, probably by an AJAX handler of some flavor.
     * Can also be called when views are embedded, as this guarantees
     * normalized output.
     */
    function preview($display_id = NULL, $args = array()) {
        if (empty($this->current_display) || ((!empty($display_id)) && $this->current_display != $display_id)) {
            if (!$this->set_display($display_id)) {
                return FALSE;
            }
        }

        $this->preview = TRUE;
        $this->pre_execute($args);
        // Preview the view.
        $output = $this->display_handler->preview();

        $this->post_execute();
        return $output;
    }

    /**
     * Run attachments and let the display do what it needs to do prior
     * to running.
     */
    function pre_execute($args = array()) {
        $this->old_view[] = views_get_current_view();
        views_set_current_view($this);
        $display_id = $this->current_display;

        // Let modules modify the view just prior to executing it.
        foreach (module_implements('views_pre_view') as $module) {
            $function = $module . '_views_pre_view';
            $function($this, $display_id, $args);
        }

        // Prepare the view with the information we have, but only if we were
        // passed arguments, as they may have been set previously.
        if ($args) {
            $this->set_arguments($args);
        }

//    $this->attach_displays();
        // Allow the display handler to set up for execution
        $this->display_handler->pre_execute();
    }

    /**
     * Unset the current view, mostly.
     */
    function post_execute() {
        // unset current view so we can be properly destructed later on.
        // Return the previous value in case we're an attachment.

        if ($this->old_view) {
            $old_view = array_pop($this->old_view);
        }

        views_set_current_view(isset($old_view) ? $old_view : FALSE);
    }

    /**
     * Run attachment displays for the view.
     */
    function attach_displays() {
        if (!empty($this->is_attachment)) {
            return;
        }

        if (!$this->display_handler->accept_attachments()) {
            return;
        }

        $this->is_attachment = TRUE;
        // Give other displays an opportunity to attach to the view.
        foreach ($this->display as $id => $display) {
            if (!empty($this->display[$id]->handler)) {
                $this->display[$id]->handler->attach_to($this->current_display);
            }
        }
        $this->is_attachment = FALSE;
    }

    /**
     * Called to get hook_menu() information from the view and the named display handler.
     *
     * @param $display_id
     *   A display id.
     * @param $callbacks
     *   A menu callback array passed from views_menu_alter().
     */
    function execute_hook_menu($display_id = NULL, $callbacks = array()) {
        // Prepare the view with the information we have.
        // This was probably already called, but it's good to be safe.
        if (!$this->set_display($display_id)) {
            return FALSE;
        }

        // Execute the view
        if (isset($this->display_handler)) {
            return $this->display_handler->execute_hook_menu($callbacks);
        }
    }

    /**
     * Called to get hook_block information from the view and the
     * named display handler.
     */
    function execute_hook_block($display_id = NULL) {
        // Prepare the view with the information we have.
        // This was probably already called, but it's good to be safe.
        if (!$this->set_display($display_id)) {
            return FALSE;
        }

        // Execute the view
        if (isset($this->display_handler)) {
            return $this->display_handler->execute_hook_block();
        }
    }

    /**
     * Determine if the given user has access to the view. Note that
     * this sets the display handler if it hasn't been.
     */
    function access($displays = NULL, $account = NULL) {
        // Noone should have access to disabled views.
        if (!empty($this->disabled)) {
            return FALSE;
        }

        if (!isset($this->current_display)) {
            $this->init_display();
        }

        if (!$account) {
            $account = $GLOBALS['user'];
        }

        // We can't use choose_display() here because that function
        // calls this one.
        $displays = (array) $displays;
        foreach ($displays as $display_id) {
            if (!empty($this->display[$display_id]->handler)) {
                if ($this->display[$display_id]->handler->access($account)) {
                    return TRUE;
                }
            }
        }

        return FALSE;
    }

    /**
     * Get the view's current title. This can change depending upon how it
     * was built.
     */
    function get_title() {
        if (empty($this->display_handler)) {
            if (!$this->set_display('default')) {
                return FALSE;
            }
        }

        // During building, we might find a title override. If so, use it.
        if (!empty($this->build_info['title'])) {
            $title = $this->build_info['title'];
        } else {
            $title = $this->display_handler->get_option('title');
        }

        return $title;
    }

    /**
     * Force the view to build a title.
     */
    function build_title() {
        $this->init_display();
        if (empty($this->built)) {
            $this->init_query();
        }
        $this->init_handlers();

        $this->_build_arguments();
    }

    /**
     * Get the URL for the current view.
     *
     * This URL will be adjusted for arguments.
     */
    function get_url($args = NULL, $path = NULL) {
        if (!isset($path)) {
            $path = $this->get_path();
        }
        if (!isset($args)) {
            $args = $this->args;
        }
        // Don't bother working if there's nothing to do:
        if (empty($path) || (empty($args) && strpos($path, '%') === FALSE)) {
            return $path;
        }

        $pieces = array();
        $arguments = isset($arguments) ? $arguments : $this->display_handler->get_option('arguments');
        $argument_keys = isset($arguments) ? array_keys($arguments) : array();
        $id = current($argument_keys);
        foreach (explode('/', $path) as $piece) {
            if ($piece != '%') {
                $pieces[] = $piece;
            } else {
                if (empty($args)) {
                    // Try to never put % in a url; use the wildcard instead.
                    if ($id && !empty($arguments[$id]['wildcard'])) {
                        $pieces[] = $arguments[$id]['wildcard'];
                    } else {
                        $pieces[] = '*'; // gotta put something if there just isn't one.
                    }
                } else {
                    $pieces[] = array_shift($args);
                }

                if ($id) {
                    $id = next($argument_keys);
                }
            }
        }

        if (!empty($args)) {
            $pieces = array_merge($pieces, $args);
        }
        return implode('/', $pieces);
    }

    /**
     * Get the base path used for this view.
     */
    function get_path() {
        if (!empty($this->override_path)) {
            return $this->override_path;
        }

        if (empty($this->display_handler)) {
            if (!$this->set_display('default')) {
                return FALSE;
            }
        }
        return $this->display_handler->get_path();
    }

    /**
     * Get the breadcrumb used for this view.
     *
     * @param $set
     *   If true, use drupal_set_breadcrumb() to install the breadcrumb.
     */
    function get_breadcrumb($set = FALSE) {
        // Now that we've built the view, extract the breadcrumb.
        $base = TRUE;
        $breadcrumb = array();

        if (!empty($this->build_info['breadcrumb'])) {
            foreach ($this->build_info['breadcrumb'] as $path => $title) {
                // Check to see if the frontpage is in the breadcrumb trail; if it
                // is, we'll remove that from the actual breadcrumb later.
                if ($path == variable_get('site_frontpage', 'node')) {
                    $base = FALSE;
                    $title = t('Home');
                }
                if ($title) {
                    $breadcrumb[] = l($title, $path, array('html' => true));
                }
            }

            if ($set) {
                if ($base) {
                    $breadcrumb = array_merge(drupal_get_breadcrumb(), $breadcrumb);
                }
                drupal_set_breadcrumb($breadcrumb);
            }
        }
        return $breadcrumb;
    }

    /**
     * Is this view cacheable?
     */
    function is_cacheable() {
        return $this->is_cacheable;
    }

    /**
     * Set up query capturing.
     *
     * db_query() stores the queries that it runs in global $queries,
     * bit only if dev_query is set to true. In this case, we want
     * to temporarily override that setting if it's not and we
     * can do that without forcing a db rewrite by just manipulating
     * $conf. This is kind of evil but it works.
     */
    function start_query_capture() {
        global $conf, $queries;
        if (empty($conf['dev_query'])) {
            $this->fix_dev_query = TRUE;
            $conf['dev_query'] = TRUE;
        }

        // Record the last query key used; anything already run isn't
        // a query that we are interested in.
        $this->last_query_key = NULL;

        if (!empty($queries)) {
            $keys = array_keys($queries);
            $this->last_query_key = array_pop($keys);
        }
    }

    /**
     * Add the list of queries run during render to buildinfo.
     *
     * @see view::start_query_capture()
     */
    function end_query_capture() {
        global $conf, $queries;
        if (!empty($this->fix_dev_query)) {
            $conf['dev_query'] = FALSE;
        }

        // make a copy of the array so we can manipulate it with array_splice.
        $temp = $queries;

        // Scroll through the queries until we get to our last query key.
        // Unset anything in our temp array.
        if (isset($this->last_query_key)) {
            while (list($id, $query) = each($queries)) {
                if ($id == $this->last_query_key) {
                    break;
                }

                unset($temp[$id]);
            }
        }

        $this->additional_queries = $temp;
    }

    /**
     * Load a view from the database based upon either vid or name.
     *
     * This is a static factory method that implements internal caching for
     * view objects.
     *
     * @param $arg
     *  The name of the view or its internal view id (vid)
     * @param $reset
     *  If TRUE, reset this entry in the load cache.
     * @return A view object or NULL if it was not available.
     */
    function &load($arg, $reset = FALSE) {
        static $cache = array();

        // We want a NULL value to return TRUE here, so we can't use isset() or empty().
        if (!array_key_exists($arg, $cache) || $reset) {
            $where = (is_numeric($arg) ? "vid =  %d" : "name = '%s'");
            $data = db_fetch_object(db_query("SELECT * FROM {views_view} WHERE $where", $arg));
            if (empty($data)) {
                $cache[$arg] = NULL;
            } else {
                $view = new view();
                $view->load_row($data);
                $view->type = t('Normal');
                // Load all of our subtables.
                foreach ($view->db_objects() as $key) {
                    $object_name = "views_$key";
                    $result = db_query("SELECT * FROM {{$object_name}} WHERE vid = %d ORDER BY position", $view->vid);

                    while ($data = db_fetch_object($result)) {
                        $object = new $object_name(FALSE);
                        $object->load_row($data);

                        // Because it can get complicated with this much indirection,
                        // make a shortcut reference.
                        $location = &$view->$key;

                        // If we have a basic id field, load the item onto the view based on
                        // this ID, otherwise push it on.
                        if (!empty($object->id)) {
                            $location[$object->id] = $object;
                        } else {
                            $location[] = $object;
                        }
                    }
                }

                $view->loaded = TRUE;
                $cache[$arg] = $view;
            }
        }

        return $cache[$arg];
    }

    /**
     * Static factory method to load a list of views based upon a $where clause.
     *
     * Although this method could be implemented to simply iterate over views::load(),
     * that would be very slow.  Buiding the views externally from unified queries is
     * much faster.
     */
    function load_views() {
        $result = db_query("SELECT DISTINCT v.* FROM {views_view} v");
        $views = array();
        $vids = array();

        // Load all the views.
        while ($data = db_fetch_object($result)) {
            $view = new view;
            $view->load_row($data);
            $view->loaded = TRUE;
            $view->type = t('Normal');
            $views[$view->name] = $view;
            $names[$view->vid] = $view->name;
        }

        // Stop if we didn't get any views.
        if (!$views) {
            return array();
        }

        $vids = implode(', ', array_keys($names));
        // Now load all the subtables:
        foreach (view::db_objects() as $key) {
            $object_name = "views_$key";
            $result = db_query("SELECT * FROM {{$object_name}} WHERE vid IN ($vids) ORDER BY vid, position");

            while ($data = db_fetch_object($result)) {
                $object = new $object_name(FALSE);
                $object->load_row($data);

                // Because it can get complicated with this much indirection,
                // make a shortcut reference.
                $location = &$views[$names[$object->vid]]->$key;

                // If we have a basic id field, load the item onto the view based on
                // this ID, otherwise push it on.
                if (!empty($object->id)) {
                    $location[$object->id] = $object;
                } else {
                    $location[] = $object;
                }
            }
        }
        return $views;
    }

    /**
     * Save the view to the database. If the view does not already exist,
     * A vid will be assigned to the view and also returned from this function.
     */
    function save() {
        if ($this->vid == 'new') {
            $this->vid = NULL;
        }

        // If we have no vid or our vid is a string, this is a new view.
        if (!empty($this->vid)) {
            // remove existing table entries
            foreach ($this->db_objects() as $key) {
                db_query("DELETE from {views_" . $key . "} WHERE vid = %d", $this->vid);
            }
        }

        $this->save_row(!empty($this->vid) ? 'vid' : FALSE);

        // Save all of our subtables.
        foreach ($this->db_objects() as $key) {
            $this->_save_rows($key);
        }

        cache_clear_all('views_urls', 'cache_views');
        cache_clear_all(); // clear the page cache as well.
    }

    /**
     * Save a row to the database for the given key, which is one of the
     * keys from view::db_objects()
     */
    function _save_rows($key) {
        $count = 0;
        foreach ($this->$key as $position => $object) {
            $object->position = ++$count;
            $object->vid = $this->vid;
            $object->save_row();
        }
    }

    /**
     * Delete the view from the database.
     */
    function delete($clear = TRUE) {
        if (empty($this->vid)) {
            return;
        }

        db_query("DELETE FROM {views_view} WHERE vid = %d", $this->vid);
        // Delete from all of our subtables as well.
        foreach ($this->db_objects() as $key) {
            db_query("DELETE from {views_" . $key . "} WHERE vid = %d", $this->vid);
        }

        cache_clear_all('views_query:' . $this->name, 'cache_views');

        if ($clear) {
            cache_clear_all(); // this clears the block and page caches only.
            menu_rebuild(); // force a menu rebuild when a view is deleted.
        }
    }

    /**
     * Export a view as PHP code.
     */
    function export($indent = '') {
        $this->init_display();
        $output = '';
        $output .= $this->export_row('view', $indent);
        // Set the API version
        $output .= $indent . '$view->api_version = \'' . views_api_version() . "';\n";
        $output .= $indent . '$view->disabled = FALSE; /* Edit this to true to make a default view disabled initially */' . "\n";

        foreach ($this->display as $id => $display) {
            $output .= $indent . '$handler = $view->new_display(' . views_var_export($display->display_plugin, $indent) . ', ' . views_var_export($display->display_title, $indent) . ', \'' . $id . "');\n";
            if (empty($display->handler)) {
                // @todo -- probably need a method of exporting broken displays as
                // they may simply be broken because a module is not installed. That
                // does not invalidate the display.
                continue;
            }

            foreach ($display->handler->option_definition() as $option => $definition) {
                // Special handling for some items
                switch ($option) {
                    case 'defaults':
                        // skip these
                        break;
                    default:
                        if (!$display->handler->is_defaulted($option)) {
                            $value = $display->handler->get_option($option);
                            if ($id == 'default') {
                                $default = isset($definition['default']) ? $definition['default'] : NULL;
                            } else {
                                $default = $this->display['default']->handler->get_option($option);
                            }

                            if ($value !== $default) {
                                $output .= $indent . '$handler->override_option(\'' . $option . '\', ' . views_var_export($value, $indent) . ");\n";
                            }
                        }
                }
            }
        }

        return $output;
    }

    /**
     * Make a copy of this view that has been sanitized of all database IDs
     * and handlers and other stuff.
     *
     * I'd call this clone() but it's reserved.
     */
    function copy() {
        $code = $this->export();
        eval($code);
        return $view;
    }

    /**
     * Safely clone a view.
     *
     * Because views are complicated objects within objects, and PHP loves to
     * do references to everything, if a View is not properly and safely
     * cloned it will still have references to the original view, and can
     * actually cause the original view to point to objects in the cloned
     * view. This gets ugly fast.
     *
     * This will completely wipe a view clean so it can be considered fresh.
     */
    function clone_view() {
        $clone = version_compare(phpversion(), '5.0') < 0 ? $this : clone($this);

        $keys = array('current_display', 'display_handler', 'build_info', 'built', 'executed', 'attachment_before', 'attachment_after', 'field', 'argument', 'filter', 'sort', 'relationship', 'query', 'inited', 'style_plugin', 'plugin_name', 'exposed_data', 'exposed_input', 'exposed_widgets', 'many_to_one_tables', 'feed_icon');
        foreach ($keys as $key) {
            if (isset($clone->$key)) {
                unset($clone->$key);
            }
        }
        $clone->built = $clone->executed = FALSE;
        $clone->build_info = array();
        $clone->attachment_before = '';
        $clone->attachment_after = '';
        $clone->result = array();

        // shallow cloning means that all the display objects
        // *were not cloned*. We must clone them ourselves.
        $displays = array();
        foreach ($clone->display as $id => $display) {
            $displays[$id] = drupal_clone($display);
            if (isset($displays[$id]->handler)) {
                unset($displays[$id]->handler);
            }
        }
        $clone->display = $displays;

        return $clone;
    }

    /**
     * Unset references so that a $view object may be properly garbage
     * collected.
     */
    function destroy() {
        foreach (array_keys($this->display) as $display_id) {
            if (isset($this->display[$display_id]->handler)) {
                $this->display[$display_id]->handler->destroy();
                unset($this->display[$display_id]->handler);
            }
        }

        foreach (views_object_types() as $type => $info) {
            if (isset($this->$type)) {
                $handlers = &$this->$type;
                foreach ($handlers as $id => $item) {
                    $handlers[$id]->destroy();
                }
                unset($handlers);
            }
        }

        if (isset($this->style_plugin)) {
            $this->style_plugin->destroy();
            unset($this->style_plugin);
        }

        // Clear these to make sure the view can be processed/used again.
        if (isset($this->display_handler)) {
            unset($this->display_handler);
        }

        if (isset($this->current_display)) {
            unset($this->current_display);
        }

        if (isset($this->query)) {
            unset($this->query);
        }
    }

    /**
     * Make sure the view is completely valid.
     *
     * @return
     *   TRUE if the view is valid; an array of error strings if it is not.
     */
    function validate() {
        $this->init_display();

        $errors = array();

        $current_display = $this->current_display;
        foreach ($this->display as $id => $display) {
            if ($display->handler) {
                if (!empty($display->deleted)) {
                    continue;
                }
                $this->set_display($id);

                $result = $this->display[$id]->handler->validate();
                if (!empty($result) && is_array($result)) {
                    $errors = array_merge($errors, $result);
                }
            }
        }

        $this->set_display($current_display);
        return $errors ? $errors : TRUE;
    }

}

/**
 * Base class for views' database objects.
 */
class views_db_object {

    /**
     * Initialize this object, setting values from schema defaults.
     *
     * @param $init
     *   If an array, this is a set of values from db_fetch_object to
     *   load. Otherwse, if TRUE values will be filled in from schema
     *   defaults.
     */
    function init($init = TRUE) {
        if (is_array($init)) {
            return $this->load_row($init);
        }

        if (!$init) {
            return;
        }

        $schema = drupal_get_schema($this->db_table);

        if (!$schema) {
            return;
        }

        // Go through our schema and build correlations.
        foreach ($schema['fields'] as $field => $info) {
            if ($info['type'] == 'serial') {
                $this->$field = NULL;
            }
            if (!isset($this->$field)) {
                if (!empty($info['serialize']) && isset($info['serialized default'])) {
                    $this->$field = unserialize($info['serialized default']);
                } else if (isset($info['default'])) {
                    $this->$field = $info['default'];
                } else {
                    $this->$field = '';
                }
            }
        }
    }

    /**
     * Write the row to the database.
     *
     * @param $update
     *   If true this will be an UPDATE query. Otherwise it will be an INSERT.
     */
    function save_row($update = NULL) {
        $schema = drupal_get_schema($this->db_table);
        $fields = $defs = $values = $serials = array();

        // Go through our schema and build correlations.
        foreach ($schema['fields'] as $field => $info) {
            // special case -- skip serial types if we are updating.
            if ($info['type'] == 'serial') {
                $serials[] = $field;
                continue;
            }
            $fields[] = $field;
            switch ($info['type']) {
                case 'blob':
                    $defs[] = '%b';
                    break;
                case 'int':
                    $defs[] = '%d';
                    break;
                case 'float':
                case 'numeric':
                    $defs[] = '%f';
                    break;
                default:
                    $defs[] = "'%s'";
            }
            if (empty($info['serialize'])) {
                $values[] = $this->$field;
            } else {
                $values[] = serialize($this->$field);
            }
        }
        $query = '';
        if (!$update) {
            $query = "INSERT INTO {" . $this->db_table . "} (" . implode(', ', $fields) . ') VALUES (' . implode(', ', $defs) . ')';
        } else {
            $query = '';
            foreach ($fields as $id => $field) {
                if ($query) {
                    $query .= ', ';
                }
                $query .= $field . ' = ' . $defs[$id];
            }
            $query = "UPDATE {" . $this->db_table . "} SET " . $query . " WHERE $update = " . $this->$update;
        }
        db_query($query, $values);

        if ($serials && !$update) {
            // get last insert ids and fill them in.
            foreach ($serials as $field) {
                $this->$field = db_last_insert_id($this->db_table, $field);
            }
        }
    }

    /**
     * Load the object with a row from the database.
     *
     * This method is separate from the constructor in order to give us
     * more flexibility in terms of how the view object is built in different
     * contexts.
     *
     * @param $data
     *   An object from db_fetch_object. It should contain all of the fields
     *   that are in the schema.
     */
    function load_row($data) {
        $schema = drupal_get_schema($this->db_table);

        // Go through our schema and build correlations.
        foreach ($schema['fields'] as $field => $info) {
            $this->$field = empty($info['serialize']) ? $data->$field : unserialize(db_decode_blob($data->$field));
        }
    }

    /**
     * Export a loaded row, such as an argument, field or the view itself to PHP code.
     *
     * @param $identifier
     *   The variable to assign the PHP code for this object to.
     * @param $indent
     *   An optional indentation for prettifying nested code.
     */
    function export_row($identifier = NULL, $indent = '') {
        if (!$identifier) {
            $identifier = $this->db_table;
        }
        $schema = drupal_get_schema($this->db_table);

        $output = $indent . '$' . $identifier . ' = new ' . get_class($this) . ";\n";
        // Go through our schema and build correlations.
        foreach ($schema['fields'] as $field => $info) {
            if (!empty($info['no export'])) {
                continue;
            }
            if (!isset($this->$field)) {
                if (isset($info['default'])) {
                    $this->$field = $info['default'];
                } else {
                    $this->$field = '';
                }

                // serialized defaults must be set as serialized.
                if (isset($info['serialize'])) {
                    $this->$field = unserialize(db_decode_blob($this->$field));
                }
            }
            $value = $this->$field;
            if ($info['type'] == 'int') {
                $value = ($info['size'] == 'tiny') ? (bool) $value : (int) $value;
            }

            $output .= $indent . '$' . $identifier . '->' . $field . ' = ' . views_var_export($value, $indent) . ";\n";
        }
        return $output;
    }

    /**
     * Add a new display handler to the view, automatically creating an id.
     *
     * @param $type
     *   The plugin type from the views plugin data. Defaults to 'page'.
     * @param $title
     *   The title of the display; optional, may be filled in from default.
     * @param $id
     *   The id to use.
     * @return
     *   The key to the display in $view->display, so that the new display
     *   can be easily located.
     */
    function add_display($type = 'page', $title = NULL, $id = NULL) {
        if (empty($type)) {
            return FALSE;
        }

        $plugin = views_fetch_plugin_data('display', $type);
        if (empty($plugin)) {
            $plugin['title'] = t('Broken');
        }


        if (empty($id)) {
            $title = $plugin['title'];

            $id = $this->generate_display_id($type);
            $count = str_replace($type . '_', '', $id);
            if (empty($title)) {
                $title = $plugin['title'] . ' ' . $count;
            }
        }

        // Create the new display object
        $display = new views_display;
        $display->options($type, $id, $title);

        // Add the new display object to the view.
        $this->display[$id] = $display;
        return $id;
    }

    /**
     * Generate a display id of a certain plugin type.
     *
     * @param $type
     *   Which plugin should be used for the new display id.
     */
    function generate_display_id($type) {
        // 'default' is singular and is unique, so just go with 'default'
        // for it. For all others, start counting.
        if ($type == 'default') {
            return 'default';
        }
        // Initial id.
        $id = $type . '_1';
        $count = 1;

        // Loop through IDs based upon our style plugin name until
        // we find one that is unused.
        while (!empty($this->display[$id])) {
            $id = $type . '_' . ++$count;
        }

        return $id;
    }

    /**
     * Create a new display and a display handler for it.
     * @param $type
     *   The plugin type from the views plugin data. Defaults to 'page'.
     * @param $title
     *   The title of the display; optional, may be filled in from default.
     * @param $id
     *   The id to use.
     * @return
     *   A reference to the new handler object.
     */
    function &new_display($type = 'page', $title = NULL, $id = NULL) {
        $id = $this->add_display($type, $title, $id);

        // Create a handler
        $this->display[$id]->handler = views_get_plugin('display', $this->display[$id]->display_plugin);
        if (empty($this->display[$id]->handler)) {
            // provide a 'default' handler as an emergency. This won't work well but
            // it will keep things from crashing.
            $this->display[$id]->handler = views_get_plugin('display', 'default');
        }

        if (!empty($this->display[$id]->handler)) {
            // Initialize the new display handler with data.
            $this->display[$id]->handler->init($this, $this->display[$id]);
            // If this is NOT the default display handler, let it know which is
            if ($id != 'default') {
                $this->display[$id]->handler->default_display = &$this->display['default']->handler;
            }
        }

        return $this->display[$id]->handler;
    }

    /**
     * Add an item with a handler to the view.
     *
     * These items may be fields, filters, sort criteria, or arguments.
     */
    function add_item($display_id, $type, $table, $field, $options = array(), $id = NULL) {
        $types = views_object_types();
        $this->set_display($display_id);

        $fields = $this->display[$display_id]->handler->get_option($types[$type]['plural']);

        if (empty($id)) {
            $count = 0;
            $id = $field;
            while (!empty($fields[$id])) {
                $id = $field . '_' . ++$count;
            }
        }

        $new_item = array(
            'id' => $id,
            'table' => $table,
            'field' => $field,
                ) + $options;

        $handler = views_get_handler($table, $field, $type);

        $fields[$id] = $new_item;
        $this->display[$display_id]->handler->set_option($types[$type]['plural'], $fields);

        return $id;
    }

    /**
     * Get an array of items for the current display.
     */
    function get_items($type, $display_id = NULL) {
        $this->set_display($display_id);

        if (!isset($display_id)) {
            $display_id = $this->current_display;
        }

        // Get info about the types so we can get the right data.
        $types = views_object_types();
        return $this->display[$display_id]->handler->get_option($types[$type]['plural']);
    }

    /**
     * Get the configuration of an item (field/sort/filter/etc) on a given
     * display.
     */
    function get_item($display_id, $type, $id) {
        // Get info about the types so we can get the right data.
        $types = views_object_types();
        // Initialize the display
        $this->set_display($display_id);

        // Get the existing configuration
        $fields = $this->display[$display_id]->handler->get_option($types[$type]['plural']);

        return isset($fields[$id]) ? $fields[$id] : NULL;
    }

    /**
     * Get the configuration of an item (field/sort/filter/etc) on a given
     * display.
     *
     * Pass in NULL for the $item to remove an item.
     */
    function set_item($display_id, $type, $id, $item) {
        // Get info about the types so we can get the right data.
        $types = views_object_types();
        // Initialize the display
        $this->set_display($display_id);

        // Get the existing configuration
        $fields = $this->display[$display_id]->handler->get_option($types[$type]['plural']);
        if (isset($item)) {
            $fields[$id] = $item;
        } else {
            unset($fields[$id]);
        }

        // Store.
        $this->display[$display_id]->handler->set_option($types[$type]['plural'], $fields);
    }

    /**
     * Set an option on an item.
     *
     * Use this only if you have just 1 or 2 options to set; if you have
     * many, consider getting the item, adding the options and doing
     * set_item yourself.
     */
    function set_item_option($display_id, $type, $id, $option, $value) {
        $item = $this->get_item($display_id, $type, $id);
        $item[$option] = $value;
        $this->set_item($display_id, $type, $id, $item);
    }

}

/**
 * A display type in a view.
 *
 * This is just the database storage mechanism, and isn't terribly important
 * to the behavior of the display at all.
 */
class views_display extends views_db_object {

    var $db_table = 'views_display';

    function views_display($init = TRUE) {
        parent::init($init);
    }

    function options($type, $id, $title) {
        $this->display_plugin = $type;
        $this->id = $id;
        $this->display_title = $title;
    }

}

/**
 * Provide a list of views object types used in a view, with some information
 * about them.
 */
function views_object_types() {
    static $retval = NULL;

    // statically cache this so t() doesn't run a bajillion times.
    if (!isset($retval)) {
        $retval = array(
            'field' => array(
                'title' => t('Fields'), // title
                'ltitle' => t('fields'), // lowercase title for mid-sentence
                'stitle' => t('Field'), // singular title
                'lstitle' => t('field'), // singular lowercase title for mid sentence
                'plural' => 'fields',
            ),
            'argument' => array(
                'title' => t('Arguments'),
                'ltitle' => t('arguments'),
                'stitle' => t('Argument'),
                'lstitle' => t('Argument'),
                'plural' => 'arguments',
            ),
            'sort' => array(
                'title' => t('Sort criteria'),
                'ltitle' => t('sort criteria'),
                'stitle' => t('Sort criterion'),
                'lstitle' => t('sort criterion'),
                'plural' => 'sorts',
            ),
            'filter' => array(
                'title' => t('Filters'),
                'ltitle' => t('filters'),
                'stitle' => t('Filter'),
                'lstitle' => t('filter'),
                'plural' => 'filters',
                'options' => 'views_ui_config_filters_form',
            ),
            'relationship' => array(
                'title' => t('Relationships'),
                'ltitle' => t('relationships'),
                'stitle' => t('Relationship'),
                'lstitle' => t('Relationship'),
                'plural' => 'relationships',
            ),
        );
    }

    return $retval;
}

/**
 * @}
 */
